From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f180.google.com (mail-ie0-f180.google.com [209.85.223.180]) by kanga.kvack.org (Postfix) with ESMTP id 101B06B0038 for ; Mon, 2 Mar 2015 21:22:30 -0500 (EST) Received: by iecrl12 with SMTP id rl12so53381719iec.4 for ; Mon, 02 Mar 2015 18:22:29 -0800 (PST) Received: from mail-ie0-x235.google.com (mail-ie0-x235.google.com. [2607:f8b0:4001:c03::235]) by mx.google.com with ESMTPS id qc2si262339igb.27.2015.03.02.18.22.29 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Mar 2015 18:22:29 -0800 (PST) Received: by iecvy18 with SMTP id vy18so53276960iec.13 for ; Mon, 02 Mar 2015 18:22:29 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20150303014733.GL18360@dastard> References: <20150302010413.GP4251@dastard> <20150303014733.GL18360@dastard> Date: Mon, 2 Mar 2015 18:22:29 -0800 Message-ID: Subject: Re: [regression v4.0-rc1] mm: IPIs from TLB flushes causing significant performance degradation. From: Linus Torvalds Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Andrew Morton , Ingo Molnar , Matt B , Linux Kernel Mailing List , linux-mm , xfs@oss.sgi.com On Mon, Mar 2, 2015 at 5:47 PM, Dave Chinner wrote: > > Anyway, the difference between good and bad is pretty clear, so > I'm pretty confident the bisect is solid: > > 4d9424669946532be754a6e116618dcb58430cb4 is the first bad commit Well, it's the mm queue from Andrew, so I'm not surprised. That said, I don't see why that particular one should matter. Hmm. In your profiles, can you tell which caller of "flush_tlb_page()" changed the most? The change from "mknnuma" to "prot_none" *should* be 100% equivalent (both just change the page to be not-present, just set different bits elsewhere in the pte), but clearly something wasn't. Oh. Except for that special "huge-zero-page" special case that got dropped, but that got re-introduced in commit e944fd67b625. There might be some other case where the new "just change the protection" doesn't do the "oh, but it the protection didn't change, don't bother flushing". I don't see it. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org